3-Chloro-4-fluoronitrobenzene is a useful compound as an intermediate for medicine and agricultural chemicals.
As industrial process for producing 3-chloro-4-fluoronitrobenzene, there has hitherto been known a process which comprises reacting 3,4-dichloronitrobenzene with excessive amount of potassium fluoride in a polar organic solvent at a high temperature. By this process, however, 3-chloro-4-fluoronitrobenzene cannot be obtained at a low cost due to the low yield and low purity, a large amount of expensive potassium fluoride used, requirement of a lot of cost for recovery of the polar organic solvent, etc.
The following reports disclose that 4-fluoronitrobenzene is subjected to chlorination to obtain 3-chloro-4-fluoronitrobenzene:
.circle.1 Chemisches Zentralblatt. 1914 II page 1432, PA1 .circle.2 Recueil des Travaux Chimiques des Pays-Bas, 51 (1932) pages 98 to 101.
According to the processes described in the reports .circle.1 and .circle.2 , 4-fluoronitrobenzene is chlorinated in the presence of ferric chloride or iron powder. These processes, however, have a defect that a large amount of dichloro-4-fluoronitrobenzene are produced as by-products in addition of aimed 3-chloro-4-fluoronitrobenzene. And there is no description in which aimed compound was obtained in a high yield in the reports.
Thus, there is demanded a development of a process comprising chlorination of 4-fluoronitrobenzene, in which 3-chloro-4-fluoronitrobenzene is obtained with a high yield with lowering the production of dichloro-4-fluoronitrobenzene as by-products.